In vivo study of the role of the cytoskeleton and fungal golgi in hyphal tip growth of Aspergillus nidulans
Bibliographic record
Abstract
Filamentous fungi, such as Aspergillus nidulans, are composed of tubular, highly polarized, multinucleate cells called hyphae. Polar growth involves secretion specifically at the hyphal tip. Secretion involves intracellular transport and co-ordination of the cytoskeleton and the endomembrane system. Intracellular transport is likely mediated by cytoskeletal elements, which, in fungal cells consist primarily of actin and microtubules (MTs). An A. nidulans strain transformed with green fluorescent protein (GFP) tagged α-tubulin was utilized in the investigation of relationship between cytoplasmic MT arrays and hyphal growth rate. A. nidulans MTs were observed to be long and flexuous and to run roughly parallel to the long axis of hyphae. No correlation between relative MT abundance and hyphal growth rate was observed, although non-growing hyphae had a lower relative MT abundance than growing hyphae. Actin depolymerization decreased hyphal growth rate while MT depolymerization did not. MT stabilization increased hyphal growth rate. Ethanol, the solvent in which the MT and actin inhibitors were dissolved, increased both average overall growth rate and growth rate variability for individual hyphae. Taxol appeared to interact with irradiation to decreased growth rate during imaging. Golgi are involved in secretion and potentially in polar growth. An A. nidulans α-coatomer protein (COP)I homolog (α-COPI), tagged with GFP, was used to investigate the role(s) of fungal Golgi in polar growth. α-COPI-GFP co-localized with the known Golgi marker, α-2,6-sialyltransferase (ST), tagged with red fluorescent protein (RFP), in untreated hyphae. Based on this observation, I propose that α -COPI-GFP can be used as a proxy for fungal Golgi localization. Fungal Golgi were more abundant at hyphal tips than subapically. Fungal Golgi forward (tipward) velocity correlated with hyphal growth rate. Fungal Golgi forward velocity was, on average, approximately ten times greater than average hyphal growth rate. Actin depolymerization reduced fungal Golgi forward velocity while MT depolymerization did not. However, MT stabilization increased fungal Golgi forward velocity. Polymerized MTs do not appear to be essential for hyphal growth but do appear to be involved in hyphal growth rate variability. MTs also appear to play some role in the movement of fungal Golgi. The distribution and movement of fungal Golgi is clearly related to polarity.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".